使用nordic平台蓝牙芯片访问spi类型的外部flash。 实现了芯片初始化，芯片/块/扇区擦除，任意地址任意长度读写，页写，掉电与唤醒功能。(Use the Nordic platform Bluetooth chip to access the SPI type external flash. It has realized chip initialization, chip / block / sector erasure, arbitrary length reading and